This invention relates generally to the guiding of a diverting shoe or pallet pin track intersection in a conveyor used in article sorting systems.
Positive displacement sortation conveyors, also known as article sorters, are well-known in the art. These systems include an article conveyor capable of handling a large volume of articles such as boxes of various sizes and weights. Where only single sided sortation is required, the conveyor uses shoes, or pallets, which are attached to either side of the slatted surface sections of the conveyor. A control determines, according to article size, the correct number of shoes required to push the article off the conveyor and onto a sortation spur which is located on one side of the conveyor. As an article that is to be discharged approaches the sortation point, the control actuates a diverter switch to displace an appropriate number of shoes onto a diagonal guide track. A lateral force is applied to the side of the article by lateral displacement of the appropriate shoes, to push the article onto the sortation spur.
A problem arises, however, when alternative tracks are adjacent on opposite lateral sides of the conveyor system. This requires a crossing of the oppositely heading guide tracks associated with the adjacent spurs. A switching system is required at the point of guide track intersection to direct the shoes through the intersection so continued force is applied to the article pushing it along the desired path.
The prior art teaches conveyor systems, such as that shown by Lauzon et al. U.S. Pat. No. 3,361,247 which utilizes a crossover pin guide, or switch, permitting lateral transfer from either the left or right side of the conveyor. The crossover switch utilizes a base plate connected to a reactivating element which acts to deflect an oncoming cam roller. The base plate is pivoted to allow the cam roller to pass through the intersection. The switch provides a positive guard against the pin being inadvertently directed into the wrong track. After being pivoted to the alternative direction or track, the switch permitted the pin to pass through in addition to providing a positive guard against the pin being inadvertently directed into the other track. Lauzon et al. was an improvement over prior art systems because the energy required to shift the position of the switch was provided by motion of the oncoming pin from the approaching shoe, or pallet, without the use of solenoids or other powered operating devices.